This invention relates to energy recovery arrangements for power electronic switches.
In many electric power converter systems, semiconductor switches capable of high frequency operation are used to control the current and voltage at the output terminals of the circuit. The development of semiconductor switches has led to devices capable of switching high currents at high frequencies. One result of such high frequency operation is increased power losses as a result of the finite turn on and turn off times of the electronic switches. In addition, high current operation results in increased power loss due to current conduction through the semiconductor switches and diodes. Both of these power loss mechanisms generate heat that must be dissipated so that the semiconductor switches are not damaged.
Manufacturers of high-power electronic switches typically provide modules containing the electronic switches and in some cases include protective circuitry but many times it is left up to the circuit designer to provide the interface between the switch module and the control circuitry. For MOS-gated switches the interface circuit contains the gate drive electronics which are necessary to turn the electronic switches on and off. This circuitry requires its own power source which is usually separate from or isolated from the main power supply to the electronic switch.
U.S. Pat. No. 5,419,780 discloses a thermoelectric generator sandwiched between a semiconductor device and a heat sink to generate electric power in response to a temperature difference between the semiconductor device and the heat sink. The power generated by the thermoelectric generator is used to operate a fan to cool the heat sink. U.S. Pat. No. 5,576,512 discloses a thermoelectric generator which is compatible with power sources providing different voltages, along with series and parallel connection circuitry for connecting the thermoelectric devices in series or in parallel depending on the voltage supplied from the power source. U.S. Pat. No. 3,316,474 describes a thermoelectric transformer for transferring electrical energy from one or more driving circuits to one or more driven circuits and U.S. Pat. No. 5,220,189 discloses a semiconductor device switched by a thermoelectric sensing element, while U.S. Pat. No. 3,252,013 discloses the use of thermoelectric devices for controlling a switch.